Animal models of human disease constitute an indispensable modality for Center Investigators. Studies of liver cell transplantation, gene therapy and hepatic pathophysiology remain a major focus of the Center. The Special Animal Core continues to thrive under Dr. Gupta's expert direction, now well into its second decade. During previous funding periods, the Core provided services to Center Investigators, as well as to investigators outside of the Liver Center and the College of Medicine. Animals are provided by the Core to facilitate studies concerning development of therapies for metabolic deficiency states, genetic liver disease, and acute or chronic liver failure. In addition, animals provided by the Core facilitate studies of hepatic gene expression, progenitor cell and stem cell biology, and liver growth control. With many studies performed in vivo, use of well-characterized animal models with unique genetic characteristics has been invaluable and will remain so in the future.